Lateral bias in infant chimpanzees (Pan troglodytes).
This study documents the presence, strength, and direction of lateralization in chimpanzees (Pan troglodytes) over the first 3 months of life. Nursery-reared chimpanzees (7 males and 5 females) were repeatedly assessed on a behavioral scale. Lateral bias was measured for 4 behaviors: hand-to-mouth, hand-to-hand, defensive grasp, and first step. Hand-to-mouth was significantly lateralized for the sample. Eight of the 10 chimpanzees that showed hand-to-mouth used the right hand. Lateral bias for defensive grasp was positively related to lateral bias both of first step and of hand-to-mouth. Lateral bias in hand-to-mouth was inversely related to lateral bias in hand-to-hand. Strength of lateralization increased as chimpanzees matured. These laterality effects in infant chimpanzees were expressed under conditions of emotional arousal. Moreover, degree of laterality may be a predictor of responsivity to stress.
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Division of Reproductive Biology, Yerkes Regional Primate Research Center, Emory University, Atlanta, Georgia 30322.
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D000818:Animals; D001143:Arousal; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007231:Infant, Newborn / Q000523:psychology*; D008297:Male; D002679:Pan troglodytes / Q000523:psychology*; D011597:Psychomotor Performance